WIP: Exposure / Light Meter app for Windows Phone 8
This code is still very much in the experimental phase. I'm still trying to figure out if it's even feasible to implement a light meter in Windows Phone.
As a result, the code is ugly! I'm going to do stuff like put everything in one codebehind class, and have all kinds of unused code lying around. Once I have the basics working, I'll refactor everything into a proper layout.
Phone cameras don't have an adjustible aperture! My Lumia 920, for example, is fixed at f/2. It appears that it adjusts light levels by varying just the ISO level and the shutter speed.
Normal cameras have 3 parameters: ISO, shutter speed, and aperture. Phone cameras merge ISO and aperture into one value, where one is derived from the other; whichever is unbound by the user.
How do I figure out what the fixed aperture value is? It varies depending on the model of phone, and there doesn't seem to be an API for getting at it. Best I can think of at this point is just taking a picture and looking in its EXIF data.